Larner, Andrew

Abstract [en]

Background: Clinical studies of alcohol and drug treatment outcomes frequently apply participanteligibility criteria (EC), which may exclude real-world treatment seekers, impairing the representativenessof studied samples. Some research exists on the impact of EC on alcohol treatment seekers.Little is known about drug treatment and country differences. Objectives: We tested and comparedthe degree to which commonly used EC exclude real-world treatment seekers with problem alcoholand drug use in Sweden and Australia, and compared the impact of EC on outcomes. Methods: Twolarge naturalistic and comparative service user samples were used. Respondents were recruited inStockholm County (n = 1,865; data collection 2000–2002), and Victoria and Western Australia (n =796; in 2012–2013). Follow-up interviews were conducted after 1 year. Cross-tabulations, Chi-square(χ2) tests and logistic regressions were used. Results: Percentages of the samples excluded byindividual EC ranged from 5% (lack of education/literacy) to 70% (social instability) among Swedishalcohol cases and from 2% (low alcohol problem severity) to 69% (psychiatric medication) amongAustralian counterparts; and from 2% (age 60+ years) to 82% (social instability) among Swedish drugcases and from 1% (age 60+ years) to 67% (psychiatric medication) among Australian counterparts.Country differences and differences across substances appeared independent of country effect.Co-morbid psychiatric medication, noncompliance, poly drug use, and low education EC causedpositive 1-year outcome bias; whereas female sex and old age introduced negative outcome bias.Conclusions/Importance: Commonly used EC exclude large proportions of treatment seekers. This mayimpair generalizability of clinical research, and the effects ofmany EC differ by country and drug type.